Radio waves: Future way to help keep e-book readers charged up?

image image Imagine a cellphone that sucks up radio waves and uses the energy to help keep batteries charged. Nokia is experimenting with such arrangements. Technology Review has details.

Now suppose the power consumption of e-paper could be even less than it is today. Could the same concept—remember, we’re talking about battery-toppers, not complete power sources—work with more advanced versions of e-book gizmos like the Sony Reader?

4 Comments on Radio waves: Future way to help keep e-book readers charged up?

  1. I don’t see this can’t work with almost any low-power electronic gadget. It’s something to look forward to.

  2. Absolutely, Steve. Of course one little detail makes me a bit nervous. If the radio waves are strong enough to power gadgets, what does this mean in terms of health risks from the same energy? Not sure. I’d love to hear people’s thoughts on this issue–the Topic Police in this case are on vacation (not that they’re that powerful anyway around here). Any interesting links people can dig up with authoritative information?


  3. Yes: Depending on the radio frequency used, there could be biologic issues… but we get bombarded with radio waves all the time, including low-power microwaves, with no ill-effects. The receiver will also be an important part of how flexible they are on which frequencies they can use to transmit power without creating biological hazards at the same time. We’ll just have to see what Nokia comes up with.

  4. This idea has been around for almost as long as radio has. I built a circuit that did this when I was a kid.

    As the article states, the amount of energy that can be extracted this way is very tiny. The 3-5 mW that Nokia is currently extracting is actually pretty good. I think they will have a tough time getting 50mW.

    Even with 50mW, this isn’t nearly enough to charge a cell phone. It will only be good for very slowly trickle charging a mostly charged device. Rechargable batteries take a significant amount of current when they are even partially discharged.

    To put this in perspective, the amount of power available from a computer’s USB port is 2.5W, which is 50 times the 50mW Nokia is aiming for. And we’re not even considering losses due to circuit/charging efficiency.

    BTW, they are talking about using “ambient” radio signals, not some high power RF that is transmitted specifically for this purpose.

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